RCW 75 is an emission nebula (H II region) in Centaurus, 13,000 light-years away
RCW 75 (Gum 48a) is an emission nebula (H II region) in the constellation Centaurus , 13,000 light-years away. spans 18′ of sky, about 68 light-years across. It is a telescope object, 6 inches or larger, and it is highest in the evening sky in May.
Nebula: a cloud of gas and dust. Emission nebulae glow on their own, lit by ultraviolet light from hot young stars; reflection nebulae shine by starlight scattered from dust; dark nebulae block the light behind them.
RCW 75 is Gum 48a in Colin Gum's survey of southern H II regions
Colin Gum listed it in his survey of H II regions of the southern Milky Way (1955), the first photographic survey of the southern emission nebulae, made at Mount Stromlo Observatory.
Finding RCW 75 from Hadar
Hadar
RCW 75
CENTAURUS
RCW 75 lies 5.7° southwest of Hadar , the magnitude 0.6 star. Three fingers held at arm's length cover about 5°.
RCW 75 is highest in the evening in May
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60°N
JAN at 60°N: -67° high at 9 pm FEB at 60°N: -54° high at 9 pm MAR at 60°N: -44° high at 9 pm APR at 60°N: -37° high at 9 pm MAY at 60°N: -33° high at 9 pm JUN at 60°N: -33° high at 9 pm JUL at 60°N: -38° high at 9 pm AUG at 60°N: -46° high at 9 pm SEP at 60°N: -58° high at 9 pm OCT at 60°N: -70° high at 9 pm NOV at 60°N: -84° high at 9 pm DEC at 60°N: -81° high at 9 pm 50°N
JAN at 50°N: -61° high at 9 pm FEB at 50°N: -47° high at 9 pm MAR at 50°N: -36° high at 9 pm APR at 50°N: -27° high at 9 pm MAY at 50°N: -23° high at 9 pm JUN at 50°N: -23° high at 9 pm JUL at 50°N: -29° high at 9 pm AUG at 50°N: -38° high at 9 pm SEP at 50°N: -51° high at 9 pm OCT at 50°N: -64° high at 9 pm NOV at 50°N: -76° high at 9 pm DEC at 50°N: -74° high at 9 pm 40°N
JAN at 40°N: -53° high at 9 pm FEB at 40°N: -39° high at 9 pm MAR at 40°N: -28° high at 9 pm APR at 40°N: -18° high at 9 pm MAY at 40°N: -13° high at 9 pm JUN at 40°N: -14° high at 9 pm JUL at 40°N: -19° high at 9 pm AUG at 40°N: -30° high at 9 pm SEP at 40°N: -43° high at 9 pm OCT at 40°N: -57° high at 9 pm NOV at 40°N: -67° high at 9 pm DEC at 40°N: -65° high at 9 pm 30°N
JAN at 30°N: -45° high at 9 pm FEB at 30°N: -31° high at 9 pm MAR at 30°N: -19° high at 9 pm APR at 30°N: -8° high at 9 pm MAY at 30°N: -3° high at 9 pm JUN at 30°N: -4° high at 9 pm JUL at 30°N: -10° high at 9 pm AUG at 30°N: -21° high at 9 pm SEP at 30°N: -35° high at 9 pm OCT at 30°N: -48° high at 9 pm NOV at 30°N: -57° high at 9 pm DEC at 30°N: -55° high at 9 pm 20°N
JAN at 20°N: -36° high at 9 pm FEB at 20°N: -22° high at 9 pm MAR at 20°N: -10° high at 9 pm APR at 20°N: 1° high at 9 pm MAY at 20°N: 7° high at 9 pm JUN at 20°N: 6° high at 9 pm JUL at 20°N: -1° high at 9 pm AUG at 20°N: -13° high at 9 pm SEP at 20°N: -26° high at 9 pm OCT at 20°N: -39° high at 9 pm NOV at 20°N: -47° high at 9 pm DEC at 20°N: -46° high at 9 pm 10°N
JAN at 10°N: -27° high at 9 pm FEB at 10°N: -13° high at 9 pm MAR at 10°N: -1° high at 9 pm APR at 10°N: 11° high at 9 pm MAY at 10°N: 17° high at 9 pm JUN at 10°N: 16° high at 9 pm JUL at 10°N: 9° high at 9 pm AUG at 10°N: -4° high at 9 pm SEP at 10°N: -18° high at 9 pm OCT at 10°N: -30° high at 9 pm NOV at 10°N: -37° high at 9 pm DEC at 10°N: -36° high at 9 pm 0°
JAN at 0°: -17° high at 9 pm FEB at 0°: -5° high at 9 pm MAR at 0°: 8° high at 9 pm APR at 0°: 20° high at 9 pm MAY at 0°: 27° high at 9 pm JUN at 0°: 26° high at 9 pm JUL at 0°: 18° high at 9 pm AUG at 0°: 5° high at 9 pm SEP at 0°: -9° high at 9 pm OCT at 0°: -20° high at 9 pm NOV at 0°: -27° high at 9 pm DEC at 0°: -26° high at 9 pm 10°S
JAN at 10°S: -8° high at 9 pm FEB at 10°S: 4° high at 9 pm MAR at 10°S: 17° high at 9 pm APR at 10°S: 30° high at 9 pm MAY at 10°S: 37° high at 9 pm JUN at 10°S: 36° high at 9 pm JUL at 10°S: 27° high at 9 pm AUG at 10°S: 14° high at 9 pm SEP at 10°S: 0° high at 9 pm OCT at 10°S: -11° high at 9 pm NOV at 10°S: -17° high at 9 pm DEC at 10°S: -16° high at 9 pm 20°S
JAN at 20°S: 1° high at 9 pm FEB at 20°S: 13° high at 9 pm MAR at 20°S: 26° high at 9 pm APR at 20°S: 39° high at 9 pm MAY at 20°S: 47° high at 9 pm JUN at 20°S: 46° high at 9 pm JUL at 20°S: 36° high at 9 pm AUG at 20°S: 23° high at 9 pm SEP at 20°S: 9° high at 9 pm OCT at 20°S: -1° high at 9 pm NOV at 20°S: -7° high at 9 pm DEC at 20°S: -6° high at 9 pm 30°S
JAN at 30°S: 11° high at 9 pm FEB at 30°S: 22° high at 9 pm MAR at 30°S: 34° high at 9 pm APR at 30°S: 48° high at 9 pm MAY at 30°S: 57° high at 9 pm JUN at 30°S: 55° high at 9 pm JUL at 30°S: 45° high at 9 pm AUG at 30°S: 32° high at 9 pm SEP at 30°S: 18° high at 9 pm OCT at 30°S: 8° high at 9 pm NOV at 30°S: 3° high at 9 pm DEC at 30°S: 4° high at 9 pm 40°S
JAN at 40°S: 20° high at 9 pm FEB at 40°S: 31° high at 9 pm MAR at 40°S: 43° high at 9 pm APR at 40°S: 57° high at 9 pm MAY at 40°S: 66° high at 9 pm JUN at 40°S: 65° high at 9 pm JUL at 40°S: 54° high at 9 pm AUG at 40°S: 40° high at 9 pm SEP at 40°S: 27° high at 9 pm OCT at 40°S: 18° high at 9 pm NOV at 40°S: 13° high at 9 pm DEC at 40°S: 14° high at 9 pm
below horizon
low
20-40°
40-60°
overhead-ish
The chart gives its height above the horizon at 9 pm through the year, from 60°N to 40°S. It can be seen from the whole southern hemisphere and north to about 27°N, and never sets south of 27°S.
RCW 75 is 13,000 light-years away
The light seen from RCW 75 tonight left it about 13,000 years ago. It ranks 43 of 47 by distance among the RCW nebulae with a measured distance. Distance source: Gaia DR2, Cantat-Gaudin 2020.
Objects within 6° of RCW 75
RCW 74, emission nebula (H II region), 1.1° RCW 78, emission nebula (H II region), 1.7° RCW 79, emission nebula (H II region), 2.5° RCW 80, supernova remnant, 3.1° RCW 73, emission nebula (H II region), 3.1° C99 Coalsack Nebula, dark nebula, 3.1° RCW 72, emission nebula (H II region), 3.4° RCW 71, emission nebula (H II region), 3.6°
RCW 75 catalog data
Field Value
Designations Gum 48a Type emission nebula (H II region) Constellation Centaurus Right ascension (J2000) 13h 19.8m Declination (J2000) -62° 31′ Apparent size 18′ True size 68 light-years Distance 13,000 light-years (Gaia DR2, Cantat-Gaudin 2020) Best month May Best with Telescope RCW number RCW 75
